Motor-control system



` Aug. 11, 1925.

H. VU. WLIJAMS MOTOR CONTROL SYSTEM Filed Sept. 8

toismeo noso il., fiile.,

MGTR-CONTRL SYSTEM..

.oppieoton filed September 8, N523. Serial No. 661,538.

To all 'wiwi/'2. may conce/ML.'

Be it known that l, inuiinio EN. lliniiiinis, u citizen of the 'UnitedStates, und u resident of W'ilkinshurg, in tho county of Allegheny andState o't Pennsylvania, have incjycnted a new unil useful improvement inMotor-Con 'trol Systems, ot which the Afollowing is :1 specification.

My invention relates to niolor-control s ys 'tc-ins ono it luisparticular relrtion to such si'slenis oi control us are employed inconnection 'with clcvz'itors, nuiufhinc tools 'und similar machines.

The oliject ot' my invention is to'proviile uicuns for controlling,r thespcccl :nul the toi-quo oi :in nltornutiiug-cuiicnt motor ol thetwo-spoed type cominoni)Y employed in oloruto': servico nml having'separato low uml high-speed windings.

ivl'y inventiiin is more particularly oppliculile to the control of utwo-speed motor of thc u'cll-linown squirrel-coge type.

in the operzliion of ulternntingwurrent `common practice to si'urt thcmotor by oonnccting its low-speed winding to the source of power unilthereafter transfer directly lo the high-speed winding, with or Withoutresisors in circuit therewith'.`

in such s yslcins, son'ie Cliliiculty has heen experienced in obtainingsmooth operation. 'in my system oi' control, i propose to start themotor lin! means of its low-speed Winti ing. Next, in transit-ion,connect the high sind lowspeed windings in parallel relation :inclprovide means 'for e suring a relatively weak'exritation of thelow-speed windings Next, the lov-spoed windings ore shuntci :nui theexcitation or 'the high-speed Wind ings is increased to its nmxii'nlnnvalue.

'To ei'licct ilccelcntliion of the motor, the spool windings :1ro firstconnected in the previously nzuneil 'parallel relation, after which thehigh-speed. windings are tlcifinei`- gironi und finally the' excitationoi' the low spool Winding is incroz sed to obtain :i miiiimuni desirableoperating speed.

iiiy invention will oe ,flosorilwfl in connection with the accompanyingdrawing, in which* l*1 igure i is n iliagiiinmutio representation ot ut\\' i -speefl, three-phase, ultornotingmurrent si'luirrol-cngo motoremployed in connecton wish. my invention,

motors ol" the type herein described, it is Fig. El is o diagrammaticrepresentation ol2 the main circuits and apparatus omhoog# ingr myinvention,

Fig'. 3 is a cliogrmnmotie representation oi' the control circuits thatarc employed in the operation of the systemshown in Fig., i?, and

Fi i is a sequence chart indicating the operation of switches employedin. Fig. 2.

Referring to the drawing, n two-speed sltmmitingcurrent motor isprovided With low-speed primary windings 2 uno. highspccil primarywindings Those windings om connected in sorics relation with opioi-:ility of reactors 1i and 5, which :we rospo@- tircly employoil forloW-specCl ond for high spoed opcrzition.` Resistor sections ti :irsar'- rangeil 'lor connection in circuit with tho higlrspccil u'inciings3 through s, switch if. A three-pile switch 8 provities moons forshouting' the. lign-speed, windings '3 nucl rendering' the iowspee.windings 2 tive. Double-pole reversing; swiohcs 9 anti 'l0 areen'iployed in the customary manner. Port ions of the low-speed reactors4; may lic shunied by a double-polo switch il that is 1no\'i le(lwith oretnrcl` g device 12.

Also, :i doublopole sWnJon i3 is orrnnge for slninting;` resistorsections t3.v This switch. is also provided wiih reminding moans. Bothswitches l1 und 13 are retarded only in ciosing. The various switchesarev operoteci. by means of a. reversiloie mostcr switch 23 of ofamiliar type having o. ,piuroiity of operati ing positions a, Z), 0 andd. A source of power supply for the motor comprises line conductors M,15 and 16. have illustrated connections for a three-phase induction motor, hut., of course, o two-pi1asc motor or mom tors of other suitabletypes nmy be similarly en i ployetl.

fi ssuining the apparatus to he in its ino@ erutice or illufitrotetlpositions, 'the motor l muy he opcrntod in an upward direction hyactuating the master switch 23 io the right.. 1in position i (seosequence chart, Fig. .l) n circuit is provide-cl for nilo/ting theclosurey of reversing swilrh und lowi spoed switch 8. Power is i nonsupplied to the motor windings 2, with reactors i in circuittherowitl'i. l" musici* swicii 23 i nmintnined in position a, switch 1iwill @losx D to shunt a portion of reactors 4l, wliereirv tl e motor isprovided with suliiclenttorque 'o fie start the desired 'maximum leed. Alight lood may be started :prior to the cllsore of switch ll.l-lovsf'erer, the primary oliiect of the @additional sections ofreactors 4. will hereinafter eppei'iif...

l/Vhen the master switch is actuated tw Werd position switch 7 fclose-s'prior to the opening of switch 8, whereupon liigli'speed Windi. C,sections in parallel relation te lov/speed windings 2. This position,eords a trensin tion peri-od or, if desired, may' Aserve es en operatingposition in 'which the motor op. erstes a speed intelinedieteits andmaximum speeds, depending upon the degree of excitetiono the low-speedWind-- ings i When the master switch 23 is moved to position t3, switchE. opens and the motor is further accelerated accordance with theexcitation of the 'windings v3. Finally switfn'i` 13 closes to shuntresistors 6, where upon the motor operates et' its maximum speed.

1t should Ifoe noted, in connection with the foregoing deeoription, thatthe goed windings ere et no time clisconnectefft nor is the power supplyinterrupted, so. het e, fairly uniform torque is developed by. the motorin accordance with the arrangement of the reactors and resistors'wl'iichare, of course, designed for limiting the currents in o,welldmown'menner. l

The motor is decelerated by returning master switch 23 toward the offposition, passing through position. o, Switch il is re closed,ree-establishing the above-described pzirsllel relation of motorwindings 2 and 3 and, upon the reopening or' switch Y, the high-speedwindings 8 deenergised and the motor is further decider-ated, since onlythe lowepeed 'windings 2 ere then energized. Switch li starts to closebut is retarded :tor e sufiicient period, whereby the torque of themotor, vf 'cli is for the moment operetins)r above its lower synchronousspeed, is suitably reduced. The etlect of the add tional reactorsections. ei, vliicli are controlled by switch ll, is to prevent o tooabrupt change in the speed of the motor, occasioned by itsregenerativeection.\ Suf cient time ailohwed for the closure of switchil so that the motor speed is first suitably reduced. vUnder,slow speedcondiw tions, ree-.eters et lieve little eliecttlpon the speedregulation ot the niotore thalt it is, ordinarily, unnecessary toprovideI for entirely sliuntingg these y"reectors from the circuit. H itis d sireble to opperste tlie motor at slowT speed forvlongt periods, enodr'itionol switch inn f lie,oi' course, pro 'vided to entirelyshunttliese 1reactors.

ceding to my invention, I ein enabled to o. :colorate ood decclerate omotor having seperate righ end low-speed windings With- Us Bereoormected through resistor.

iis-sectie out disconnecting these windin whereby" :i fairly uniformtorque ,is obtoineiiie and, con-- seqoently, smooth and liexible speedcontrol. Also, the switching arrangement is such that the lineconductors cannot be short-circuited by failure of on of thespeed-controlling switches to function.

In the arrangement of a porotos, as illus treted in Fig. 2, itispossiiile to provide ior a different sequence vof operation and toobtiin still other operating speeds as, .for esempio, when both. thehigh and low-speed switches vand 8 are open, `sind the motor windingsare 'all' connected in series relation. Resistors ma be substituted inplace vot" reactors 4 an 5 when,y desirable, but I prefer to emnlo tilearrangement illustrated, particularly or hoisting Aapplications.

.Operation of the motor ine reverse direetipo. is obtained in a mannersimilar to that described above, u on the' closure of reversing switch10 in p ace of reversing switch 9 by the meniprdation of master switch2f to the left, through positions c ond. o?, es will be readilyiriderstood.

lieve described and illustrated my in vent on in simple term, butvarious mod. ilN

eotions roede therein Without deport-- ing; i'roro. tile spirit and.scope thereof.

claire es my invention:

The method oi accelerating en' alter nstingrorrent motor having low andhigh; speed windings connected' in series relotion,

fliicli consists in shouting the liiiglirspeed windings, connecting seidhigh ond lov?u speed windings parallel relation, diiniiin isliing; theeffect ol? said low-sneed Windinfs and .finally shouting; seidloivspeerl Winch ings.

'.llie method of acceleraiting en ini. if tion motor lowing low andhigh-speed Wi dings connected in series relation, Wliicli oon siste inenergizing tlie losv-speed windings, connecting; seid low end high-speedwind ings in 'parallel relation, lcssening the eilcct ot seid low-speedwindings, and ifinelly, shooting sind low-speed windings.

The method of decelereting an elternoting-ourrent motor having 4low andbiglispeed windings connected in series relation, which consists inconnecting the loir ond high-speed windings in partllel relation whenthe eect oi' the low-speed windings is crelatively Weak, disconnectingseid highspeed windings and strengthening the effect the low-speedwindings.

el. The combination with en alfernatingcnrrent motor' having low andhiglispeed windings connected in series relation, endg reactorsalternating in/position'witli soif windings, oi' means for selectivelysiiiintiorf seid windings zindior connect-ing; said Winch ings inparallel relation Without intcrmptM ingr the motor circuit.

5. The combination with en alternetingn` Til current motor having'lowand high-sneed 'windings connected in series relation, and

ing said windings.

G, The Combination with an alternatingourre'nt motor having lowl andhigh-speed windings connected in series relation, and

Leurrent-liiniting means alternating in posi-v tion with said windings,vof means for selectively shunting said windings and for conneoting saidwindings in parallel' relation VWithout.interrupting the inotor circuit.

7. The combination with an alternating- Current motor having low andhigh-speed windings connected in series relation, and

current-limiting means alternating -in position with said windings, ofmeans for selectively sliunting said windings and for oonneeting lsaidwindings in parallel relation without disconnecting said windings.

8. 'The combination with an alternatingeuri-ent motor having low andhigh-speed windings Connected in series relation, and reactors incircuit with saidI windings, of means Comprising said reactors forselectively sliunting said windings and for oon- .neeting said windingsprogressively in series and in parallel relation without ingthe motorcircuit.

ln testimony whereof I have hereunto subscribed my Anaine this 13th dayof August, 1923.

HAROLD W. WILLIAMS.

30 interrnpt- A,

